Adsorption Of Streptavidin Research Articles

Electron beam patterning of biomolecules

The patterning of biomolecules on semiconducting surfaces is of central importance in the fabrication of novel biodevices. In the process of patterning, it is required that the biomolecule preserves its properties and the substrate is not damaged by the chemicals, the temperatures or the patterning beams involved in the procedure. Recently, both DUV and electron beam microlithography have been used in order to deposit protein layers in predefined patterns. Various approaches have been used, some involving photoresists. Contrast between exposed and unexposed regions, resolution of adjacent features and sensitivity to dose variation, are the key issues. The approach followed in this paper consists of a direct patterning of a biotin layer, deposited on an amino-silane primed silicon nitride surface, using an electron beam. After irradiation, the surface is covered by bovine serum albumin (BSA), which acts as a blocking material to protect the exposed areas from streptavidin adsorption. Using 20 keV e-beam energy and doses, in the range 100–1000 μC/cm 2, submicrometer dense lines of 1-μm pitch have been obtained. The results have been tested by fluorescence optical microscopy.

Functionalization of Carbon Nanotubes for Biocompatibility and Biomolecular Recognition

The interface between biological molecules and novel nanomaterials is important to developing new types of miniature devices for biological applications. Here, the streptavidin/biotin system is used to investigate the adsorption behavior of proteins on the sides of single-walled carbon nanotubes (SWNTs). Functionalization of SWNTs by coadsorption of a surfactant and poly(ethylene glycol) is found to be effective in resisting nonspecific adsorption of streptavidin. Specific binding of streptavidin onto SWNTs is achieved by co-functionalization of nanotubes with biotin and protein-resistant polymers. Recent years have witnessed a significant interest in biological applications of novel solid-state nanomaterials. 1-6 The unique physical properties of molecular- or nanoscale solids (dots or wires) when utilized in conjunction with the remarkable biomolecular recognition capabilities could lead to miniature biological electronics and optical devices including probes and sensors. Not only could these devices exhibit advantages over existing technology in size but also in performance. Several issues are important regarding nanomaterial/biosystems. One of them is biocompatibility, especially for in-vivo applications of implantable bioelectronic devices. Another is specificity that requires biofunctionalization of nanomaterials for recognition of only one type of target biomolecule in solution and rejection of others. Central to tackling these issues is surface functionalization of nanomaterials and elucidating the interfaces and interactions between nanomaterials and biosystems. Single-walled carbon nanotubes (SWNTs) are novel molecular scale wires exhibiting useful properties for various potential applications including miniature biological devices. For instance, nanotubes can be used as electrodes for detecting biomolecules in solutions, similar to commonly used conventional carbon based electrode materials. Also, the electrical properties of SWNTs are sensitive to surface charge transfer and changes in the surrounding electrostatic environment, undergoing drastic changes by simple adsorptions of certain molecules or polymers. 7-10 SWNTs are therefore promising for chemical sensors for detecting molecules in the gas phase and biosensors for probing biological processes in solutions. Nevertheless, significant effort is required in order to understand interactions between nanotubes and biomolecules and how to impart specificity and selectivity to nanotube-based bioelectronic devices. Motivated by the biological application prospects of solidstate nanomaterials, this work investigates (1) nonspecific binding (NSB) of proteins to SWNTs, (2) functionalization of nanotubes for resisting nonspecific interactions, and (3) enabling specific binding of proteins to functionalized nanotubes. We find that streptavidin nonspecifically binds to as-grown SWNTs and show that prevention of NSB of streptavidin on SWNTs is achieved by coating nanotubes with a surfactant and poly(ethylene glycol), PEG. Selective binding of streptavidin is introduced by co-functionalization of SWNTs with PEG and biotin. The results have implications to the nanotube biocompatibility 11 issue and specificity of potential bioelectronic devices based on nanotubes. In an earlier communication, we have shown that protein binding to SWNTs is reliably enabled via a noncovalent sidewall functionalization scheme. 5 In this manner, a variety

Simulation of two-dimensional streptavidin crystallization.

We present lattice Monte Carlo simulations of the growth of streptavidin islands at a biotinylated lipid layer. The model employed takes into account attractive anisotropic lateral interactions between streptavidin tetramers. With a minimal set of interactions, we reproduce the formation of rectangular islands experimentally observed at pH > or = 9.0. Specifically, we analyze two scenarios of the island growth. First, if streptavidin is rapidly adsorbed at t = 0 (stepwise coverage change without ongoing adsorption), the average linear island size is found to grow according to the Lifshitz-Slyozov law, R proportional to t(1/3). Second, if the island growth occurs in parallel with streptavidin adsorption limited by diffusion in the solution, the Lifshitz-Slyozov law is also applicable, but only at the late stage, when the streptavidin coverage is appreciable.

Colloidal gold as an electrochemical label of streptavidin–biotin interaction

A new electrochemical method to monitor biotin–streptavidin interaction, based on the use of colloidal gold as an electrochemical label, is investigated. Biotinylated albumin is adsorbed on the pretreated surface of a carbon paste electrode (CPE). This modified electrode is immersed in colloidal gold–streptavidin labelled solutions. Adsorptive voltammetry is used to monitor colloidal gold bound to streptavidin, obtaining a good reproducibility of the analytical signal (R.S.D.=3.3%). A linear relationship between peak current and streptavidin concentration from 2.5×10 −9 to 2.5×10 −5 M is obtained when a sequential competitive assay between streptavidin and colloidal gold-labelled streptavidin is carried out. On the other hand, the adsorption of streptavidin on the electrode surface was performed, followed by the reaction with biotinylated albumin labelled with colloidal gold. In this way, a linear relationship between peak current and colloidal gold labelled biotinylated albumin concentration is achieved with a limit of detection of 7.3×10 9 gold particles per ml (5.29×10 −9 M in biotin).

Voltammetric monitoring of the interaction between streptavidin and biotinylated alkaline phosphatase through the enzymatic hydrolysis of 3-indoxyl phosphate

The streptavidin–biotin interaction was monitored on the surface of a pre-treated carbon paste electrode (CPE). This study has been accomplished for the estimation of the sensitivity of the alkaline phosphatase/3-indoxyl phosphate (AP/3-IP) couple when it was used as a detection scheme in voltammetric affinity devices. The enzymatic turnover of the substrate gives indigo, which shows two reversible electrode processes at potentials around −0.4 and +0.3 V (versus Ag/AgCl) in a 0.1 M Tris buffer solution pH 7.2. The peak current of the second reduction process constitutes the analytical signal. Two different approaches have been developed. The first one was based on the passive adsorption of streptavidin on the electrode surface and subsequent reaction with AP-labelled biotin (B-AP). The calibration curve obtained for this reaction, and expressed in terms of AP concentration, exhibits a linear dynamic range from 10 −13 to 10 −11 M, with a detection limit of 2×10 −13 M ( S/ N=3). These results were compared with those calculated when the labelled biotin was adsorbed directly on the electrode surface. The second approach was focused on the development of a carbon paste probe for the detection of biotin hydrazide, based on a sequential competitive assay format. A calibration curve in the range of 10 −13–10 −11 M was obtained with an estimated detection limit of 3×10 −13 M.

The specific adsorption of streptavidin to a tetrabiotinylated porphyrin monolayer at the air-water interface

The specific interaction at the air-water interface between streptavidin and a monolayer of the tetrabiotinylated ligand 5,10,15,20-tetrakis {α-[4-(biotinylamidomethyl)pyridinium bromide]-p-tolyl porphyrin, stabilised by complexation with sodium octadecyl sulphate, is observed directly by surface pressure measurements and by fluorescence microscopy. Changes in the structure of the monolayer, especially the appearance of domains, after adding protein to the subphase confirm that the concomitant expansion of the pressure-area isotherm is caused by the specific adsorption of protein to biotin ligands in the monolayer.

Binding of Biotinylated DNA to Streptavidin-Coated Polystyrene Latex

The binding of 5′-end biotinylated DNA fragments was compared between streptavidin (SA)-coated commercial. M-280 magnetic latex particles with a diameter of 2.8 μm and adsorption-coated polystyrene (PS) latex standard particles whose diameter is 0.272 μm. Amino acid analysis showed the protein content of the commercial particles to correspond to 4× monolayer coverage, while the adsorption-coated PS particles displayed monolayer coverage, or 8 pmol/cm 2. A fluorescence-based method was developed to quantify the adsorption of FITC-labeled SA, biotin, and biotinylated DNA. The validity of the method was substantiated for the labeled protein by both amino acid analysis and a colorimetric protein assay. While the specific binding of biotin was 0.38 mol per mole of SA on the adsorption-coated 0.272-μm particles and slightly higher (0.6 mol per mole SA) on the 2.8-μm particles, the specific binding of the bulky biotinylated 300-bp DNA was more favorable on the smaller particle (0.12 mol per mole SA for 0.272 μm versus 0.04 mol per mole SA for 2.8 μm).

The use of streptavidin-biotinylglycans as a tool for characterization of oligosaccharide-binding specificity of lectin

A new rapid and sensitive method for characterizing lectin specificity using streptavidin-biotinylglycans as a tool is presented. This assay is analogous to enzyme immunoassay and takes advantage of the strong, irreversible adsorption of streptavidin to the wells of the chambers of titer plates. A series of streptavidin-biotinylglycans was first coated on a microtiter plate, and then one of six lectins, concanavalin A, wheat germ agglutinin, Phaseolus vulgaris (red kidney bean) erythroagglutinin, Lens culinaris (lentil) agglutinin, Datura stramoniun agglutinin, or Sambucus nigra (elderberry bark) agglutinin coupled to horseradish peroxidase, was added. After incubation and thorough washing, only the lectin bound to a complementary glycan remained and could be detected and quantified by the peroxidase reaction. It was established that the lectins retained their oligosaccharide-binding specificities after coupling to the peroxidase, that the binding was inhibited by addition of the corresponding sugar inhibitors, and that the color intensity produced by the enzyme reaction is proportional to the amount of lectin-peroxidase bound to biotinylglycan complexed with streptavidin immobilized on the plate. As an example, it was found that the peroxidase- D. stramoniun agglutinin conjugate strongly bound biotinylglycans, GlcNAc 3-Man 5- R, GalGlcNAc 3Man 5- R, and GlcNAc 3–4Man 3- R ( R = GlcNAc 2-[6-(biotinamido)hexanoyl]-Asn). As little as 10 pmol/ml of lectin was detected. With the growing availability of biotinylglycans, the method should represent a reliable and simple procedure for screening lectin-oligosaccharide recognition qualitatively and quantitatively.

Custom ICs spread their influence : Roderic Beresford and Harvey J. Hindin. Electronics, 93 (5 May 1982)

The patterning of biomolecules on semiconducting surfaces is of central importance in the fabrication of novel biodevices. In the process of patterning, it is required that the biomolecule preserves its properties and the substrate is not damaged by the chemicals, the temperatures or the patterning beams involved in the procedure. Recently, both DUV and electron beam microlithography have been used in order to deposit protein layers in predefined patterns. Various approaches have been used, some involving photoresists. Contrast between exposed and unexposed regions, resolution of adjacent features and sensitivity to dose variation, are the key issues. The approach followed in this paper consists of a direct patterning of a biotin layer, deposited on an amino-silane primed silicon nitride surface, using an electron beam. After irradiation, the surface is covered by bovine serum albumin (BSA), which acts as a blocking material to protect the exposed areas from streptavidin adsorption. Using 20 keV e-beam energy and doses, in the range 100–1000 μC/cm2, submicrometer dense lines of 1-μm pitch have been obtained. The results have been tested by fluorescence optical microscopy.

Comparison of GaAs device approaches for ultrahigh-speed VLSI : Richard C. Eden. Proc. IEEE70 (1), 5 (1982)

The patterning of biomolecules on semiconducting surfaces is of central importance in the fabrication of novel biodevices. In the process of patterning, it is required that the biomolecule preserves its properties and the substrate is not damaged by the chemicals, the temperatures or the patterning beams involved in the procedure. Recently, both DUV and electron beam microlithography have been used in order to deposit protein layers in predefined patterns. Various approaches have been used, some involving photoresists. Contrast between exposed and unexposed regions, resolution of adjacent features and sensitivity to dose variation, are the key issues. The approach followed in this paper consists of a direct patterning of a biotin layer, deposited on an amino-silane primed silicon nitride surface, using an electron beam. After irradiation, the surface is covered by bovine serum albumin (BSA), which acts as a blocking material to protect the exposed areas from streptavidin adsorption. Using 20 keV e-beam energy and doses, in the range 100–1000 μC/cm2, submicrometer dense lines of 1-μm pitch have been obtained. The results have been tested by fluorescence optical microscopy.

Iminobiotin affinity columns and their application to retrieval of streptavidin.

A method is described for the retrieval of streptavidin from the culture broth of Streptomyces avidinii. The key step in this procedure is the adsorption of streptavidin from culture concentrates to an affinity column in which iminobiotin is attached to AH-Sepharose 4B. This column binds streptavbidin at pH 11 and releases the protein at pH 4. The recovery of streptavidin is practically quantitative. The pH dependence of the iminobiotin-avidin affinity, discovered by Green [Green, N. M. (1966) Biochem. J. 101, 774-779], has thus found practical application. The streptavidin bound 4.07 +/- 0.02 mol of [14C]biotin per mol and was essentially homogeneous as judged by disc and slab gel electrophoresis. Streptavidin was extensively succinoylated without loss of biotin-binding capacity. The observations that 125I-labeled streptavidin and 125I-labeled succinoylstreptavidin are retained by iminobiotin-AH-Sepharose 4B columns at pH 7.5 and are eluted at pH 4.0 provides a convenient purification method for these iodinated proteins. The technique employed for the retrieval of streptavidin is generally applicable to the isolation of iminobiotinylated molecules.